GB2201995A - Locks - Google Patents

Abstract

The throwing mechanism of a cylinder mortice lock is adapted to achieve an increased length of throw for a given cam radius. To this end the drive slot 10, instead of being cut directly in the bolt tail, is provided in a separate drive member 9 pinned to the bolt at 11 and constrained to move along an arcuate track 14. The drive member 9 therefore serves effectively to amplify the movement of the cylinder cam 16 with respect to the bolt 3. As the drive member 9 rocks around the cylinder 15 as the bolt is extended and retracted it is also possible to include extended flank angles on the drive member without fouling the cylinder. <IMAGE>

Description

Locks The present invention relates to locks. In particular, the invention is concerned with means for converting the rotary movement of a key bit, cylinder cam or other like operating member in a lock mechanism into linear movement of a dead bolt, by which the length of throw imparted to the bolt for a given radius of the operating member can be increased in comparison with conventional bolt-throw mechanisms.

The invention aims to provide a solution to the conflicting requirements of a compact lock mechanism capable of fitting within the narrow casings frequently demanded by presentday architectural practice, and a bolt having a sufficiently long throw to resist securely the forcing loads which may be placed upon the door or other closure to which it is fitted. In a conventional bolt-throw mechanism the rotating operating member engages in an essentially rectangular cut-out or drive slot provided in the tail of the bolt to extend and retract the bolt by abutment with the opposite faces of that slot in accordance with the direction in which the operating member is turned.

To increase the throw of the bolt for a given radius of the operating member the edges of the drive slot in the bolt tail which define the limits of the abutment with the operating member should be brought closer to the line parallel to the direction of bolt movement which passes through the axis of rotation of the operating member. The extent to which the bolt throw can be increased in this way is, however, limited by various factors. For example, there is a limit on the proximity of the drive slot edges to the axis of the operating member beyond which the operating member will simply jam in the slot when it is turned. Another limitative factor comes into play when it is desired to include a so-called flank angle (or talon form) on the bolt.By this is meant an arcuate surface which extends from each edge of the drive slot proper to follow the locus of the operating member past the point where it disengages from the respective drive face of the slot when extending or retracting the bolt, these surfaces being provided to ensure, by coacting with the operating member, that the bolt cannot be inadvertently moved or deliberately manipulated during those portions of the rotation of the operating member just before or after it shifts the bolt and while the deadlocking means for the bolt are already or still released. If the edges of the drive slot proper are located in relation to the operating member at-the optimum position for maximising the length of the bolt throw, problems may arise with the extended flank angle surfaces fouling the operating member (or the structure from which it extends) during movement of the bolt.This is particularly so where the operating member is the cam of a locking cylinder, the body of which would obstruct the movement of the flank angle surfaces with the bolt.

One known technique to increase the throw of a bolt for a given radius of the operating member is to incorporate a so-called fly talon. By this is meant an auxiliary member for engagement with the drive slot in the bolt, which is pivoted about an axis below that of the primary operating member in relation to the bolt and has a drive slot of its own with which the primary operating member engages. The turning radius of this additional member is thus greater than that of the primary operating member so that its interposition in the transmission of motion from the primary operating member to the bolt effectively serves to amplify the movement of the primary operating member with respect to the bolt in comparison with the case where the primary locking member engages directly with the bolt.

This mechanism is relatively bulky, however, as the fly talon extends to the bolt from below the keyhole or locking cylinder and must be of a size to accommodate the key or cylinder cam for rotation in an aperture within it. It is not suitable, therefore, when space within the lockcase is at a premium.

The invention seeks to overcome these problems of the prior art in a mechanism aiming for increased bolt-throw and accordingly provides a lock comprising: a linearly reciprocable bolt; a, drive member pivotally connected to the bolt and having a drive slot therein for cooperation with a rotary operating member; the drive member being borne in an arcuate track having a centre of curvature which lies beyond the axis of rotation of the operating member with respect to the bolt; whereby rotation of the operating member is effective to reciprocate the bolt through the agency of the drive member, with the drive member pivoting relative to the bolt so as to rock its drive slot around the turning operating member as the bolt is extended and retracted.

In such a mechanism the drive member achieves an effective amplification of the movement of the operating member with respect to the bolt - and thus an increased bolt-throw - in a manner geometrically akin to the conventional fly talon.

The bearing arrangement for this drive member, however, obviates the need for a physical pivot on the remote side of the operating member and hence results in a much more compact mechanism overall. Furthermore by thus providing the drive slot in a separate member which rocks the slot (and any flank angle extending from itj in an arcuate path around the operating member as the latter turns, the edges of the drive slot can be located so as to further enhance the length of the bolt throw without the drive member fouling the operating member (or the structure, e.g.

locking cylinder, from which it extends) as the bolt moves.

These and other features of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an "exploded" view of components of a lock including a bolt-throw mechanism in accordance with the invention; Figures 2-5 are views.of the mechanism in successive stages during the extension of the dead bolt of the lock; and Figures 6-7 are views of the mechanism in successive stages during the retraction of an additional spring bolt.

Referring to Figures 1-5 the illustrated lock is a cylinder-operated mortice deadlock with a casing 1 and forend 2 through which the head of a bolt 3 can be extended and retracted. The bolt 3 can be deadlocked in its extended and retracted positions by a detainer 4 borne for sliding in a groove 5 in the bolt perpendicular to the direction of movement of the bolt itself, and having a head 6 for cooperation with a racking slot 7 in the casing. A spring 8 biases the detainer 4 to its lower (deadlocking) position. A drive member 9 with a drive slot 10 is pivoted on a pin 11 fixed to the bolt. The drive member 9 has an arcuate rib 13 on its reverse (as viewed) face by which it is borne to slide along an arcuate guide slot 14 in the casing; in the illustrated embodiment the centre of curvature of the slot 14 lies just at the lower edge of the casing 1. A conventional profile locking cylinder 15 is fixed to the casing in known manner.

Figure 2 shows the disposition of these components in the retracted condition of the bolt 3, the head 6 of the detainer in this position lying in the pocket 7A of the racking slot 7 to deadlock the bolt. To extend the bolt the correct key is inserted in the locking cylinder 15 to release its plug and is turned to rotate the cylinder cam 16 through one complete revolution in the anti-clockwise sense (as viewed in the drawings). As the cam 16 turns it first encounters the detainer 4 and lifts the latter against the bias of the spring 8 to release the detainer head 6 from the pocket 7A. As the detainer is being lifted the cam 16 passes adjacent to a flank angle 17 on the drive member 9 to ensure that unwanted bolt movement cannot occur.Further turning of the cam brings it to the position shown in Figure 3 in which it abuts the drive face 10A of the slot 10 and, with the detainer 4 still lifted, drives the member 9 alongits slot 14, through the position shown in Figure 4, to throw out the bolt to its extended position shown in Figure 5, by virtue of the pinned connection between the drive member and bolt. In Figure 5 the cam is shown in the position in which it has disengaged from the drive face 10A and is permitting the detainer 4 to drop under the bias of spring 8, to deadlock the bolt once more'with the detainer head 6 now in the pocket 7B of slot 7. During the latter movement the cam passes adjacent to a second flank angle 18 on the drive member to ensure that unwanted bolt movement cannot occur.

Retraction of the bolt 3 from its extended position is the reverse of the above sequence, with the cylinder cam 18 driving the member 9 back along its slot 14 by abutment with the drive face 10B of the slot 10.

It will be appreciated from the Figures that by virtue of the arcuate movement of the drive member 9 as the bolt is extended and retracted it effectively amplifies the movement of the cylinder cam 16 with respect to the bolt.

Furthermore, as the drive member rocks around the cylinder cam 16 it keeps the flank angles 17, 18 from abutting the body of the cylinder 15 - as they would do if moving in a straight line between the Figures 2 and 5 positions. In this way an increased bolt throw is made possible as compared to an equivalent cam 16 engaging directly in a drive slot in the bolt so that high strength locking can be achieved while retaining a compact bolt-throw mechanism capable of fitting in a narrow case. By way of example, a mechanism as illustrated in the drawings with a case depth of 55mm and height of 90mm can produce a bolt throw of 16mm.

Turning to Figures 6 sod 7, these show a modification to the lock whereby an additional spring bolt can be withdrawn by a further part clockwise turn of the key after withdrawal of the dead bolt 3. In this case an additional vertical slide 19 is borne in a groove 20 in the dead bolt 3 and is positioned so that its lower end lies in the path of the cylinder cam 16 when the latter is turned clockwise with the dead bolt in its retracted position. This action lifts the slide 19 from its Figure 6 to its Figure 7 position so that a cam surface 21 at its upper end turns a follower (not shown) connected to the spring bolt.

Claims (7)

1. A lock comprising: a linearly reciprocable bolt; a drive member pivotally connected to the bolt and having a drive slot therein for cooperation with a rotary operating member; the drive member being borne in an arcuate track having a centre of curvature which lies beyond the axis of rotation of the operating member with respect to the bolt; whereby rotation of the operating member is effective to reciprocate the bolt through the agency of the drive member, with the drive member pivoting relative to the bolt so as to rock its drive slot around the turning operating member as the bolt is extended and retracted.

2. A lock according to claim 1 wherein said arcuate track is constituted by a slot in the casing of the lock, within which a projection on the drive member is received.

3. A lock according to claim 1 or claim 2 wherein the drive member has flank angles extending to each side of its drive slot.

4. A lock according to any preceding claim wherein the bolt carries a detainer which normally serves to block the bolt against movement but which is lifted to an unblocking position by rotation of the operating member.

5. A lock according to any preceding claim incorporating a locking cylinder of which the cam constitutes said operating member.

6. A lock according to any preceding claim further comprising a spring-biased bolt which can be retracted by operation of an actuating member carried by the firstmentioned bolt; said actuating member being operated by rotation of said operating member in the same sense as that in which it retracts the first-mentioned bolt and being placed in a position for engagement by the operating member when the first-mentioned bolt is in its retracted position.

7. A lock substantially as hereinbefore described with reference to Figures 1-5 or Figures 6 and 7 of the accompanying drawings.